Diagnostic sensitivity of pleural fluid cytology in malignant pleural effusions: systematic review and meta-analysis

BACKGROUND

Pleural fluid cytology is an important diagnostic test used for the investigation of pleural effusions. There is considerable variability in the reported sensitivity for the diagnosis of malignant pleural effusions (MPE) in the literature.

OBJECTIVE

The purpose of this review is to determine the diagnostic sensitivity of pleural fluid cytology for MPE, both overall and by tumour type, to better inform the decision-making process when investigating pleural effusions.

DATA SOURCES

A literature search of EMBASE and MEDLINE was performed by four reviewers. Articles satisfying inclusion criteria were evaluated for bias using the QUADAS-2 tool.

DATA EXTRACTION

For quantitative analysis, we performed a metaanalysis using a binary random-effects model to determine pooled sensitivity. Subgroup analysis was performed based on primary cancer site and meta-regression by year of publication.

SYNTHESIS

Thirty-six studies with 6057 patients with MPE were included in the meta-analysis. The overall diagnostic sensitivity of pleural fluid cytology for MPE was 58.2% (95% CI 52.5% to 63.9%; range 20.5%-86.0%). There was substantial heterogeneity present among studies (I² 95.5%). For primary thoracic malignancies, sensitivity was highest in lung adenocarcinoma (83.6%; 95% CI 77.7% to 89.6%) and lowest in lung squamous cell carcinoma (24.2%; 95% CI 17.0% to 31.5%) and mesothelioma (28.9%; 95% CI 16.2% to 41.5%). For malignancies with extrathoracic origin, sensitivity was high for ovarian cancer (85.2%; 95% CI 74.2% to 96.1%) and modest for breast cancer (65.3%; 95% CI 49.8% to 80.8%).

CONCLUSIONS

Pleural fluid cytology has an overall sensitivity of 58.2% for the diagnosis of MPE. Clinicians should be aware of the high variability in diagnostic sensitivity by primary tumour type as well as the potential reasons for false-negative cytology results.PROSPERO registration numberCRD42021231473.

Airway inflammation in severe asthmatics with acid gastro-oesophageal reflux

The relationship between childhood asthma and gastro-oesophageal reflux (GOR) is contentious. Recent studies in adult asthmatics suggest that GOR is associated with worse control and differences in sputum proteomics related to epithelial integrity, systemic inflammation and host defence. We assessed 127 children with severe asthma undergoing bronchoscopy and pH study. There were no differences in asthma control or measures of airway inflammation or remodelling when those with acid GOR were compared with those without. These results suggest that acid GOR is not an important comorbidity in paediatric severe asthma.

Rat model of smoke inhalation-induced acute lung injury

BACKGROUND

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is a lethal disease with limited therapeutic options and an unacceptably high mortality rate. Understanding the complex pathophysiological processes involved in the development of ALI/ARDS is critical for developing novel therapeutic strategies. Smoke inhalation (SI) injury is the leading cause of morbidity and mortality in patients with burn-associated ALI/ARDS; however, to our knowledge few reliable, reproducible models are available for pure SI animal model to investigate therapeutic options for ALI/ARDS without the confounding variables introduced by cutaneous burn or other pathology.

OBJECTIVE

To develop a small animal model of pure SI-induced ALI and to use this model for eventual testing of novel therapeutics for ALI.

METHODS

Rats were exposed to smoke using a custom-made smoke generator. Peripheral oxygen saturation (SpO₂), heart rate, arterial blood gas, and chest X-ray (CXR) were measured before and after SI. Wet/dry weight (W/D) ratio, lung injury score and immunohistochemical staining of cleaved caspase 3 were performed on harvested lung tissues of healthy and SI animals.

RESULTS

The current study demonstrates the induction of ALI in rats after SI as reflected by a significant, sustained decrease in SpO₂ and the development of diffuse bilateral pulmonary infiltrates on CXR. Lung tissue of animals exposed to SI showed increased inflammation, oedema and apoptosis as reflected by the increase in W/D ratio, injury score and cleaved caspase 3 level of the harvested tissues compared with healthy animals.

CONCLUSION

We have successfully developed a small animal model of pure SI-induced ALI. This model is offered to the scientific community as a reliable model of isolated pulmonary SI-induced injury without the confounding variables of cutaneous injury or other systemic pathology to be used for study of novel therapeutics or other investigation.

Bronchoscopic needle-based confocal laser endomicroscopy (nCLE) as a real-time detection tool for peripheral lung cancer

INTRODUCTION

Diagnosing peripheral lung cancer with the bronchoscope is challenging with near miss of the target lesion as major obstacle. Needle-based confocal laser endomicroscopy (nCLE) enables real-time microscopic tumour visualisation at the needle tip (smart needle).

AIM

To investigate feasibility and safety of bronchoscopic nCLE imaging of suspected peripheral lung cancer and to assess whether nCLE imaging allows real-time discrimination between malignancy and airway/lung parenchyma.

METHODS

Patients with suspected peripheral lung cancer based on (positron emission tomography-)CT scan underwent radial endobronchial ultrasound (rEBUS) and fluoroscopy-guided flexible bronchoscopy. After rEBUS lesion detection, an 18G needle loaded with the CLE probe was inserted in the selected airway under fluoroscopic guidance. The nCLE videos were obtained at the needle tip, followed by aspirates and biopsies. The nCLE videos were reviewed and compared with the cytopathology of the corresponding puncture and final diagnosis. Five blinded raters validated nCLE videos of lung tumours and airway/lung parenchyma twice.

RESULTS

The nCLE imaging was performed in 26 patients. No adverse events occurred. In 24 patients (92%) good to high quality videos were obtained (final diagnosis; lung cancer n=23 and organising pneumonia n=1). The nCLE imaging detected malignancy in 22 out of 23 patients with lung cancer. Blinded raters differentiated nCLE videos of malignancy from airway/lung parenchyma (280 ratings) with a 95% accuracy. The inter-observer agreement was substantial (κ=0.78, 95% CI 0.70 to 0.86) and intra-observer reliability excellent (mean±SD κ=0.81±0.05).

CONCLUSION

Bronchoscopic nCLE imaging of peripheral lung lesions is feasible, safe and allows real-time lung cancer detection. Blinded raters accurately distinguished nCLE videos of lung cancer from airway/lung parenchyma, showing the potential of nCLE imaging as real-time guidance tool.

Pulmonary vascular proliferation in patients with severe COVID-19: an autopsy study

Diffuse alveolar damage and thrombi are the most common lung histopathological lesions reported in patients with severe COVID-19. Although some studies have suggested increased pulmonary angiogenesis, the presence of vascular proliferation in COVID-19 lungs has not been well characterised. Glomeruloid-like microscopic foci and/or coalescent vascular proliferations measuring up to 2 cm were present in the lung of 14 out of 16 autopsied patients. These lesions expressed CD31, CD34 and vascular endothelial cadherin. Platelet-derived growth factor receptor-β immunohistochemistry and dual immunostaining for CD34/smooth muscle actin demonstrated the presence of pericytes. These vascular alterations may contribute to the severe and refractory hypoxaemia that is common in patients with severe COVID-19.

Histopathological findings in fatal COVID-19 severe acute respiratory syndrome: preliminary experience from a series of 10 Spanish patients

In December 2019, an outbreak of severe acute respiratory syndrome associated to SARS-CoV2 was reported in Wuhan, China. To date, little is known on histopathological findings in patients infected with the new SARS-CoV2. Lung histopathology shows features of acute and organising diffuse alveolar damage. Subtle cellular inflammatory infiltrate has been found in line with the cytokine storm theory. Medium-size vessel thrombi were frequent, but capillary thrombi were not present. Despite the elevation of biochemical markers of cardiac injury, little histopathological damage could be confirmed. Viral RNA from paraffin sections was detected at least in one organ in 90% patients.

Applications of artificial intelligence and machine learning in respiratory medicine

The past 5 years have seen an explosion of interest in the use of artificial intelligence (AI) and machine learning techniques in medicine. This has been driven by the development of deep neural networks (DNNs)-complex networks residing in silico but loosely modelled on the human brain-that can process complex input data such as a chest radiograph image and output a classification such as 'normal' or 'abnormal'. DNNs are 'trained' using large banks of images or other input data that have been assigned the correct labels. DNNs have shown the potential to equal or even surpass the accuracy of human experts in pattern recognition tasks such as interpreting medical images or biosignals. Within respiratory medicine, the main applications of AI and machine learning thus far have been the interpretation of thoracic imaging, lung pathology slides and physiological data such as pulmonary function tests. This article surveys progress in this area over the past 5 years, as well as highlighting the current limitations of AI and machine learning and the potential for future developments.

Lung cryobiopsy and interstitial lung disease: What is its role in the era of multidisciplinary meetings and antifibrotics?

Diagnosing ILD can be complex, and despite detailed evaluation and HRCT imaging, many patients require lung biopsy to help classify their disease. SLB has served as the reference standard for histopathology in ILD, since initial classification schemes were created more than 50 years ago. Frequently, patients are too unwell to undertake SLB and remain unclassifiable, despite the input of expert MDD. This can limit access to therapy and establishment of prognosis. TBLC is an emerging procedure for sampling lung tissue with promising results in research and clinical settings. Although diagnostic yield is not as high as SLB, the risk profile looks to be more acceptable and the accuracy appears to be good. There is increasing evidence for the utility of cryobiopsy in ILD diagnosis, particularly within the MDD. Cryobiopsy serves as an important adjunct for the diagnosis of ILD, enhancing the diagnostic confidence of treating clinicians.

FLCN-regulated miRNAs suppressed reparative response in cells and pulmonary lesions of Birt-Hogg-Dubé syndrome

Background

Birt-Hogg-Dubé Syndrome (BHDS) characterised by skin fibrofolliculomas, kidney tumour and pulmonary cysts/pneumothorax is caused by folliculin (FLCN) germline mutations. The pathology of both neoplasia and focused tissue loss of BHDS strongly features tissue-specific behaviour of the gene. Isolated cysts/pneumothorax is the most frequent atypical presentation of BHDS and often misdiagnosed as primary spontaneous pneumothorax (PSP). Deferential diagnosis of BHDS with isolated pulmonary presentation (PSP-BHD) from PSP is essential in lifelong surveillance for developing renal cell carcinoma.

Methods

The expression profiles of microRNAs (miRNAs) in cystic lesions of PSP-BHD and PSP were determined via microarray. The selected upregulated miRNAs were further confirmed in the plasma of an expanded cohort of PSP-BHD patients by reverse transcription quantitative PCR (RT-qPCR). Their diagnostic accuracy was evaluated. Moreover, the cellular functions and targeted signalling pathways of FLCN-regulated miRNAs were assessed in various cell lines and in the lesion tissue contexts.

Results

Cystic lesions of PSP-BHD and PSP showed different miRNAs profiles with a significant upregulation of miR-424–5p and let-7d-5p in PSP-BHD. The combination of the two effectively predicted BHDS patients. In vitro studies revealed a suppressive effect of FLCN on miR-424–5p and let-7d-5p expressions specifically in lung epithelial cells. The ectopic miRNAs triggered epithelial apoptosis and epithelial transition of mesenchymal cells and suppressed the reparative responses in cells and tissues with FLCN deficiency.

Conclusion

The upregulation of miR-424–5p and let-7d-5p by FLCN deficiency occurred in epithelial cells and marked the PSP-BHD condition, which contributed to a focused degenerative pathology in the lung of PSP-BHD patients.

Altered airway ciliary orientation in patients with X-linked retinitis pigmentosa

Previous reports suggested links between respiratory ciliary dysfunction and primary ciliopathies such as X-linked retinitis pigmentosa (XLRP). To investigate if patients with XLRP have abnormal airway ciliary structure or function, we assessed respiratory ciliary beat pattern and ultrastructure, including ciliary orientation, in 12 patients with XLRP without respiratory disease and 10 control subjects. Patients with XLRP had normal ciliary ultrastructure but significantly (p=0.004) increased mean ciliary deviation (33.8°±9.4°) compared with normal subjects (14.8°±5.4°). Altered orientation was associated with impaired ciliary beat pattern in six patients with XLRP. These findings indicate that XLRP mutations, affecting non-motile cilia of the photoreceptors in the retina, can have effects on motile cilia in the respiratory tract. The observation of disrupted ciliary orientation in patients with XLRP is suggestive of a defect in planar cell polarity.

Virtual bronchoscopic navigation as an aid to CT-guided transbronchial biopsy improves the diagnostic yield for small peripheral pulmonary lesions

BACKGROUND AND OBJECTIVE

Virtual bronchoscopic navigation (VBN) entails the provision of a virtual display of the bronchial routes that lead to small peripheral pulmonary lesions (PPL). It has been predicted that a combination of computed tomography (CT)-guided transbronchial biopsy (CT-TBB) with VBN might improve the diagnostic yield for small PPL. This study sought to investigate that prediction.

METHODS

A total of 100 patients with small PPL (<20 mm) were enrolled for CT-TBB and randomly allocated to either a VBN+ or VBN- group (50 subjects per group). Group results were then compared in terms of diagnostic yield, whole procedure time, times at which the first CT scan and biopsy were taken and the number of lung biopsy specimens retrieved.

RESULTS

The diagnostic yield for small PPL was significantly higher in the VBN+ group versus VBN- group (84% vs 58%, respectively (P = 0.013)), with no significant difference in (whole) examination time between groups (VBN+: 32:53 (32 min and 53 s) ± 12:01 vs VBN-: 33:06 ± 10:08 (P = NS)). However, the time periods between commencing the examination and either the first CT scan or first biopsy were significantly shorter for the VBN+ group, while the net biopsy time tended to be longer for this group with a significantly higher number of specimens collected (VBN+: 3.54 ± 1.07 specimens vs VBN-: 2.98 ± 1.06 specimens (P = 0.01)).

CONCLUSION

Combining VBN with CT-TBB significantly improved the diagnostic yield for small PPL.

Image enhancement technology in bronchoscopy: a prospective multicentre study in lung cancer

Introduction

Patients with lung cancer may present with additional lesions in the central airways. Earlier studies have shown a relationship between vessel diameter, pattern and grade of malignancy. High-definition (HD+) bronchoscopy with image enhancement techniques (i-scan) detected more vascular abnormalities but correlation with pathology has not yet been established.

Methods

In this investigator-initiated, randomised, controlled, crossover, multicentre study in patients with suspected lung cancer, a HD+ bronchoscopy was performed with i-scan1 and i-scan2 settings in random order. Biopsies, visual grade and vascular pattern classification were obtained by endoscopists and blinded evaluation.

Results

In 107 patients, vascular patterns were classified in 48 tumours. Abrupt-ending vessels were predominantly found in squamous cell carcinoma but overall correlation between vessel pattern and histology was not significant (p=0.339). Additional lesions were detected in 35 patients (33%) with a correlation between vessel pattern and high-grade (pre-)invasive lesions (p<0.001). In 8.4% of the patients, relevant second lesions were detected which determined treatment and staging in 3% of all patients. Interobserver agreement was excellent for visual grading of the airway epithelium, but low for classifying vascular patterns. No significant detection rate difference was found by blinded and unblinded evaluation.

Conclusion

HD+ bronchoscopy with i-scan image enhancement readily detects additional lesions. In one-third of all the patients, additional lesions were detected. Their vascular pattern correlates to pathology outcome, but the interobserver correlation for vascular pattern classification is low. These lesions were relevant in 8.4% and affected treatment and work-up in 3% of the cases.

Trial registration number

NCT02285426; Results.

Increased heterogeneity of airway calibre in adult rats after hypoxia-induced intrauterine growth restriction

BACKGROUND AND OBJECTIVE

Intrauterine growth restriction (IUGR) is associated with asthma development. We hypothesized that IUGR disrupts airway development leading to postnatal structural abnormalities of the airway that predispose to disease. This study therefore examined structural changes to the airway and lung in a rat model of maternal hypoxia-induced IUGR.

METHODS

Pregnant rats were housed under hypoxic conditions (11.5% O₂ ) from gestational days (GDs) 13 to 20 (pseudoglandular-canalicular stages, i.e. period of airway development) and then returned to normoxic conditions (21% O₂ ). A control group of pregnant rats was housed under normoxic conditions throughout pregnancy. Weights of male offspring were recorded at birth and 7 weeks of age (adulthood), at which point lungs were fixed for morphometry and stereology (n = 6/group), or bronchoalveolar lavage fluid (BALF) was collected for cell counts (n = 6/group).

RESULTS

IUGR offspring were lighter at birth compared with control, but not at 7 weeks. While there was no difference in mean airway dimensions or lung volume, there was greater anatomical variation in airway lumen area in the IUGR group. A mathematical model of the human lung was used to show that greater heterogeneity in lumen area in IUGR-affected individuals increases bronchoconstriction during simulated bronchial challenge. More macrophages were identified in the BALF of IUGR offspring.

CONCLUSION

The rat model demonstrates that IUGR leads to a more heterogeneous distribution of airway lumen calibre in adulthood with potential implications for bronchoconstriction in human subjects. Together with increased lung macrophages, these findings support a phenotypic shift after IUGR that may impact disease susceptibility.

Nasal lavage, blood or sputum: Which is best for phenotyping asthma?

BACKGROUND AND OBJECTIVE

Determination of asthma phenotypes, particularly inflammatory phenotypes, helps guide treatment and management of this heterogeneous disease. Induced sputum cytology has been the gold standard for determination of inflammatory phenotypes, but sputum induction is fairly invasive and technically challenging. Blood and nasal lavage cytology have been suggested as substitutes, but have not been fully verified. The aim of this study is to determine the accuracy of blood and nasal lavage cytometry as indicators of inflammatory phenotypes in asthma.

METHODS

Clinical evaluation, Asthma Control Questionnaire (ACQ) and spirometry were performed for 121 adult asthma patients, and blood, nasal lavage and induced sputum samples were taken. Eosinophils and neutrophils were counted in three samples from each subject. Inflammatory phenotypes (eosinophilic, neutrophilic, mixed and paucicellular) and cells counts were analysed using Venn diagram and receiver operating characteristic (ROC) curve, respectively.

RESULTS

ACQ score, spirometry and bronchodilator response did not differ among subjects with different inflammatory phenotypes. Inflammatory phenotypes defined by nasal lavage cytometry were in better concordance than those defined by blood cell counts with phenotypes determined by sputum cytology, and were significantly correlated with sputum phenotypes. For eosinophilia, nasal lavage cytology showed better accuracy than blood cytology (area under the curve (AUC): 0.89 vs 0.65). For all phenotypes, sensitivity and positive and negative predictive power were higher for nasal lavage cytometry than for blood. Blood cell counts gave a high level of false positives for all inflammatory phenotypes.

CONCLUSION

We recommend nasal lavage cytology over blood cell count as a substitute for sputum cytology to identify inflammatory phenotypes in asthma.

Rapid on-site evaluation with the Hemacolor rapid staining method of medical thoracoscopy biopsy specimens for the management of pleural disease

BACKGROUND AND OBJECTIVE

Medical thoracoscopy (MT) is useful for the management of pleural disease. Rapid on-site evaluation (ROSE) of transbronchial needle aspirates proved to be useful during bronchoscopy. We aimed to evaluate the diagnostic performance of ROSE of MT biopsy specimens and thoracoscopists' impression of the macroscopic appearance and assess the intermodality agreement between ROSE and final histopathologic diagnosis.

METHODS

Sixty two patients with exudative pleural effusions further investigated with MT were enrolled. MT was performed under local anaesthesia and conscious sedation, using the rigid pleuroscope. ROSE with the Hemacolor rapid staining method of the biopsy specimens was performed. Thoracoscopists' impression of the macroscopic appearance was recorded. The final diagnosis was established following histopathological examination.

RESULTS

Thoracoscopic pleural biopsies were diagnosed in 61 patients (98.4%). Group A (n = 25) consisted of patients with malignancy and group B (n = 37) with benign disorders. Area under the curve of ROSE for the diagnosis of malignancy was 0.86 (95% CI: 0.76-0.96, P < 0.001), with a sensitivity of 79.17%, specificity of 94.59%, diagnostic accuracy of 88.5%, positive predictive value of 90.5% and negative predictive value of 87.5%. Intermodality agreement between ROSE and histopathology was good (κ ± SE = 0.615 ± 0.084, P < 0.001). Area under the curve of the thoracoscopists' impression of macroscopic appearance was 0.72 (95% CI: 0.58-0.85, P = 0.001), with a sensitivity of 100%, specificity of 44.7%, positive predictive value of 53.33% and negative predictive value of 100%.

CONCLUSION

Rapid on-site evaluation during MT was found to have high accuracy for predicting malignancy. ROSE can provide the thoracoscopist with an on-site preliminary diagnosis, especially in cases with inconclusive macroscopic appearance.

Comparison of two 22 G aspiration needles for histologic sampling during endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA)

OBJECTIVE

Endobronchial ultrasound-guided transbronchial needle aspiration is widely used for mediastinal and hilar lesions. Histologic specimens from this procedure are important for specific diagnosis and targeted therapy. Studies on the traditional endobronchial ultrasound-guided transbronchial needle aspiration needles reported yields of only 50-60% for diagnostic histologic specimens. Recently, a new needle has become available in Europe, USA and Asia. The investigators aimed to evaluate the histologic specimen retrieval yields of the two needles.

METHODS

Patients who underwent endobronchial ultrasound-guided transbronchial needle aspiration with the new 22 G needle (M group, n = 94) were compared with a historical control group who underwent endobronchial ultrasound-guided transbronchial needle aspiration with the traditional 22 G needle (O group, n = 82). The quality of needle aspirates from both groups was evaluated.

RESULTS

There were no significant differences between the two groups in terms of demographics, lesion characteristics, primary disease and examiner experience. The M group had a significantly shorter procedure time than the O group (P = 0.049). Of the 214 punctures by the M group, 159 (74.3%) were diagnostic, 28 (13.1%) were non-diagnostic and 27 (12.6%) had no histologic specimen. The 235 punctures by the O group were diagnostic in 144 (61.3%), non-diagnostic in 60 (25.5%) and had no histologic specimen in 31 (13.2%). The yield for diagnostic histologic specimens of the M group was significantly higher than the O group (P = 0.0035). There were no major complications observed.

CONCLUSIONS

The yield for diagnostic histologic specimens by the new 22 G endobronchial ultrasound-guided transbronchial needle aspiration needle was high. Further technical improvements of histologic sampling yields are very important when selecting targeted therapy.